Have We Signed Ilunga?

The official site has a round-up by Scott Duxbury on the transfer window. In the statement Duxbury says,

"Having also exercised the option to keep Herita Ilunga at the club long-term, we are very happy with the business we have done."

Did we sign Ilunga permanently without my realising? Surely the club would have made more of this if we had signed Ilunga on a permanent deal.